1. Field of the Invention
The present invention relates to photosensitive switches, and more particularly to photosensitive switches incorporated into a two-dimensional array, that switches element by element in response to light, the array also incorporating a memory means and a readout means.
2. Discussion and the Background Art
In prior art three-dimensional imaging, range finding by light strip techniques is typically utilized. In a conventional light stripe ranging system a range map is obtained by projecting a light stripe onto a scene, obtaining a camera image of the scene, extracting the projected stripe position, and stepping the light stripe and repeating the process until the entire scene has scanned, thus forming a single resultant 3D image of the entire scene.
In a second type of three-dimensional camera, a fan-shaped beam of light originating from a source located to the side of receiving aperture of the camera sweeps across the field of view, once for each frame time/exposure time of the camera. The light beam from the field of view falls on a photosensitive array in the camera that activates a switch and thereby records element by element the time when the light beam was sensed. This second type system is described in U.S. Pat. No. 5,107,103 discussed below.
U.S. Pat. No. 5,107,103 issued Apr. 21, 1992 to Gruss et al. entitled "Integrated Circuit Having At Least A Sensor And A Processor Thereon" describes a circuit that may be employed in an image scanning system having an integrated circuit that comprises a sensor which produces a sensor signal corresponding to energy received. The integrated circuit is also comprised of a processing element connected to the sensor which receives the sensor signal only from the sensor and produces a processed signal corresponding to the sensor signal. Additionally, there is a memory connected to the processing element for receiving the processed signal and storing the processed signal. In a preferred embodiment, the integrated circuit is also comprised of a buffer connected to the sensor and the processing element for receiving the sensor signal and buffering the sensor signal for reception by the processing element. The sensor can include a photodiode which receives the sensor signal corresponding to light energy it receives. In a more preferred embodiment, the integrated circuit includes a photosensitive array comprised of cells for use in a light stripe rangefinder wherein a plane of light is moved across a scene. Each cell is able to detect and remember the time at which it observes the increased light intensity thereon.
U.S. Pat. No. 5,118,180 issued Jan. 2, 1992 to Wichmann et al., entitled "Method And Apparatus For Determining The Range Of Vision Of A Motor Vehicle Driver Upon Encountering Fog Or Other Obstacles" describes a method and apparatus for determining the range of vision of the driver of a motor vehicle upon encountering a fog. A transmitter and receiving member are mounted on the front portion of the motor vehicle. A series of beams are transmitted from the rangefinder to different measured portions of the roadway. The reflections from the roadway are monitored. When the atmospheric conditions change so that a fog or other obstacle appears in the roadway, the reflected signal will take on different characteristics or will not appear at all. The driver of the motor vehicle can have a visual and/or an acoustic warning indication inside the vehicle to note that some dangerous conditions exists.
Background references that relate to three-dimensional imaging using a time/distance feature of a laser to obtain the depth/range/distance dimension of an image or scene include U.S. Pat. No. 3,682,553 issued Aug. 8, 1972 to Kapany entitled "Apparatus For Acquiring And Laying Real Time 3-D Information"; U.S. Pat. No. 4,199,253 issued Apr. 22, 1980 to Ross entitled "Methods And Systems For Three-Dimensional Measurement"; U.S. Pat. No. 4,708,473 issued Nov. 24, 1987 to Metzdorff et al. entitled "Acquisition of Range Images"; U.S. Pat. No. 4,854,698 issued Aug. 8, 1989 to Schmidt entitled "3-D Measurement Via Multiple Gating"; U.S. Pat. No. 4,967,270 issued Oct. 30, 1190 to Ulich et al. entitled "Lidar System Incorporating Multiple Cameras For Obtaining A Plurality Of Subimages" and U.S. Pat. No. 5,110,203 issued May 5, 1992 to MacCabee entitled "Three Dimensional Range Imaging".
Background references that describe electro-optical relays include U.S. Pat. No. 4,902,901 issued Feb. 20, 1990 to Pernyeszi entitled "High-Power Solid State Relay Employing Photosensitive Current Augmenting Means For Faster Turn-On Time"; U.S. Pat. No. 4,912,335 issued Mar. 27, 1990 to Ehalt et al. entitled, "Means For Rapid Charging And Dynamic Discharging Of A Capacitively Charged Electrical Device"; U.S. Pat. No. 4,931,656 issued Jun. 5, 1990 to Ehalt et al. entitled, "Means To Dynamically Discharge A Capacitively Charged Electrical Device"; and U.S. Pat. No. 4,939,375 issued Jul. 3, 1990 to Walters et al. entitled "Solid State Relay With Shield Means".